The definition of irretrievable is something that cannot be retrieved, restored, fixed or put right.
When your computer hard drive permanently loses all your data, this is an example of a time when the data is irretrievable.
that cannot be retrieved, recovered, restored, or recalled
Difficult or impossible to retrieve or recover: Once the ring fell down the drain, it was irretrievable.
- ir′re·triev′a·ble·ness, ir′re·triev′a·bil′i·ty